This invention relates to a V-belt automatic transmission and more particularly to an improved construction for such a transmission.
V-belt automatic transmissions are used for a variety of purposes. Such transmissions include a split pulley having one pulley half that is axially fixed to the associated shaft and another pulley half that is axially movable relative to the shaft. A V-belt is received between the pulley halves and the speed ratio of the transmission is determined by the axial distance between the pulley halves and, accordingly, the radial distance of the V-belt relative to the associated shaft. A mechanism is provided for axially moving the axially movable pulley half in response to the shaft speed. In one type of transmission of this general type, the speed responsive mechanism is contained within an area defined by one of the pulley halves and a closure cap that is affixed to this pulley half. Such an arrangement provides a compact assembly and one which protects the internal components of the speed responsive mechanism and also affords some safety to the associated components from damage by the rotating components.
With this type of transmission there is a certain amount of frictional heat generated by the slippage between the V-belt and the pulley halves. The heat generated is increased under high torque and high load conditions. The enclosure of the speed responsive elements by means of a cap, as aforenoted, can prevent the dissipation of the generated heat. Therefore, such V-belt transmissions must be provided with a mechanism for cooling. One form in which such cooling has been accomplished is through the provision of cooling air openings in the enclosing cap. However, the provision of cooling air openings in the cap does not always insure adequate cooling since it is difficult to insure the appropriate amount of air flow through the respective openings. Various fan-like devices have, therefore, been proposed to insure adequate cooling air. These devices not only increase the weight of the unit but also its cost.
Another way of insuring adequate cooling would be to delete the enclosing cap. However, when this is done the components of the speed responsive mechanism are exposed and can cause concern on the part of the operator of damage. Furthermore, when the open construction is employed some arrangement is required to insure rigidity of the elements which are used to transfer the rotational force between the movable pulley half and the shaft. This function is normally provided by the cap in the enclosed type of transmission mechanism.
It is, therefore, a principal object of this invention to provide an improved V-belt type of automatic transmission.
It is another object of the invention to provide a V-belt automatic transmission of the generally enclosed type and which nevertheless is adequately cooled.